Catalyst for preparation of unsaturated aldehyde and unsaturated carboxylic acid

ABSTRACT

A catalyst suited for catalytic vapor-phase oxidation of isobutylene, t-butanol or propylene to produce respectively corresponding unsaturated aldehyde and unsaturated carboxylic acid is provided. Said catalyst consists of ring-formed shaped bodies composed of (i) a catalyst composition containing at least molybdenum and bismuth as the active ingredients and (ii) inorganic fibers. The catalyst excels in mechanical strength, can give the object products at high yield and shows little activity degradation with time.

TECHNICAL FIELD TO WHICH THE INVENTION BELONGS

[0001] This invention relates to catalyst for preparation of unsaturatedaldehyde and unsaturated carboxylic acid. More particularly, theinvention relates to a catalyst which is suitable for use in productionof methacrolein and methacrylic acid, or acrolein and acrylic acid, byvapor-phase catalytic oxidation of isobutylene, tertiary butanol (whichhereafter may be identified as t-butanol) or propylene. The inventionalso relates to processes for producing these unsaturated aldehydes andunsaturated carboxylic acids, using said catalyst.

PRIOR ART

[0002] Many proposals have been made for catalysts to be used in theoccasion of vapor-phase catalytic oxidation of isobutylene, t-butanol orpropylene to produce respectively corresponding unsaturated aldehyde andunsaturated carboxylic acid.

[0003] It is already known that the yield improves when the catalystshape is changed from pellets to rings. For example, JP 59 (1984)-46132A (=U.S. Pat. No. 4,511,671 A, EP 102,641 A1) has disclosed, as meritsof adopting a specific ring form: (1) conversion improves due toincrease in geometrical surface area, (2) yield improves because thereduced catalyst wall thickness enhances heat-removing effect, (3)pressure loss decreases, and (4) catalyst life is extended due todecrease in thermal load. For still increasing these effects, thinningthe ring thickness is preferred. Reduction in the thickness, however,invites decrease in mechanical strength and causes such problems as, forexample, when finished ring-formed catalyst is kept in a drum can, thecatalyst at the bottom of the can break and become useless, or they maybreak when they are charged in reaction tubes and scattering in pressureloss among the reaction tubes increases.

[0004] As a method for improving strength of catalysts, it is known toadd a fibrous material. For example, JP 51(1976)-20357 B relating tovanadium pentoxide catalyst, copper-chromic acid catalyst,nickel-diatomaceous earth catalyst and manganese-chromic acid catalyst,discloses a method of adding a fibrous material, for example, blueasbestos, to the catalyst powder obtained through drying or calcinationand subsequent pulverization. However, effect of adding a fibrousmaterial to catalysts comprising molybdenum and bismuth as the essentialingredients is unknown. Also as to ring-formed catalyst, addition offibrous material gives rise to a problem of increased scattering inmechanical strength among individual catalyst rings, while theirmechanical strength can be improved.

[0005] JP 59 (1984)-183832 A (=U.S. Pat. No. 4,564,607 A) discloses amethod of using whiskers having an average diameter not more than 5 μmas a reinforcement, in preparation of heteropolyacid-based catalyst.Whereas, as to catalyst comprising molybdenum and bismuth as theessential ingredients, addition of whiskers results in yield reduction,while improving catalyst strength.

[0006] JP 6 (1994)-381 A (=U.S. Pat. No. 5,532,199 A, EP 574,895 A1)discloses a method of using inorganic fibers having an average diameterof 2-200 μm as assistant carrier, in preparing carried catalystcontaining molybdenum and bismuth as essential ingredients. This methodaims at preparation of carried catalyst in which the carrier carries alarge amount of the catalyst, and for that purpose a method ofpreparation must be such that a slurry formed by dispersingcatalytically active ingredients and inorganic fibers in a liquid isdeposited on a carrier and at the same time the liquid is vaporized andevaporated. This preparation method, however, is not necessarily easy ofoperating, and the catalytic activity varies depending on variation inpreparation conditions. Hence, there is a problem of difficulty inpreparing catalyst which exhibits uniform catalytic performance.

[0007] Problems To Be Solved By The Invention

[0008] Accordingly, therefore, the object of the present invention is tosolve the above problems in the prior art, by providing a catalystsuitable for catalytic vapor-phase oxidation of isobutylene, t-butanolor propylene to produce corresponding unsaturated aldehyde andunsaturated carboxylic acid, i.e., a catalyst which excels in mechanicalstrength, is capable of providing the object products at high yield, andshows little deterioration in catalytic performance with time.

[0009] Means to Solve the Problems

[0010] Through our research work we have come to find that a catalystfor production of unsaturated aldehyde and unsaturated carboxylic acid,which is obtained by shaping a catalyst composition containing as activeingredients at least molybdenum and bismuth into rings and whichadditionally contains in the catalyst composition inorganic fibers suchas glass fiber, alumina fiber, silica fiber, carbon fiber and the like,can accomplish the above object. The present invention is completedbased on the above knowledge.

[0011] Thus, according to the invention, a catalyst for production ofunsaturated aldehyde and unsaturated carboxylic acid is provided, whichis characterized in that it consists of ring-shaped bodies comprising acatalytic composition containing as active ingredients at leastmolybdenum and bismuth, and inorganic fibers.

[0012] According to the invention, furthermore, a process is provided,which is characterized by using the above catalyst in catalyticvapor-phase oxidation of isobutylene, tertiary butanol or propylene withmolecular oxygen, whereby producing respectively correspondingmethacrolein and methacrylic acid or acrolein and acrylic acid.

[0013] The reason why the addition of inorganic fibers according to thepresent invention achieves improvements not only in the catalyst'smechanical strength but also in the catalytic performance, as well asinhibition of catalyst's deterioration with time is not fully clear yet.Presumably, because the catalyst composition is diluted with theinorganic fibers, the heat generated during the reaction is dispersed,sequential reactions are inhibited, and thermal degradation of thecatalyst is inhibited. Also in view of the observation that theimprovement in the catalyst's mechanical strength is achieved when theadded inorganic fibers have a specific size, it is presumed that theinorganic fibers are adequately dispersed in the catalyst to maintain anadequately mixed and contacted condition with the catalyst composition.

[0014] Embodiments of the Invention

[0015] The catalyst of the present invention is of the type normallyreferred to as shaped catalyst, which is in the form of ring-shapedcatalyst made of a catalyst composition containing molybdenum andbismuth as essential ingredients, and inorganic fibers. It is not a socalled carried catalyst, formed by carrying a catalyst composition on acarrier.

[0016] As typical examples of the catalyst composition, those expressedby the following general formula (1) may be named:

MO_(a)Bi_(b)Fe_(c)A_(d)B_(e)O_(x)  (1)

[0017] (in which Mo is molybdenum; Bi is bismuth; Fe is iron; A is atleast one element selected among nickel and cobalt; B is at least anelement selected among alkali metal elements, alkaline earth metalelements, thallium, phosphorus, tellurium, antimony, tin, cerium, lead,niobium, manganese, arsenic, zinc, silicon, aluminium, titanium,zirconium and tungsten; O is oxygen; a, b, c, d, e and x stand for therespective atomic numbers of Mo, Bi, Fe, A, B and 0, where a is 12, b is0.1-10, c is 0.1-20, d is 2-20; e is 0-30 and x is a numerical valuedetermined by the extents of oxidation of the other elements).

[0018] The catalyst composition expressed by the general formula (1) canbe formulated following those methods generally used for preparing thistype of catalyst. As the starting materials of each of the ingredients,oxides of the ingredients or salts of the ingredients which form oxidesunder heating, such as nitrates, ammonium salts, organic acid salts,carbonates, alkali metal salts and the like, may be suitably selectedfor use.

[0019] As inorganic fibers, glass fibers, ceramic fibers, carbon fibersand the like may be used, of those, glass fibers, alumina fibers andsilica fibers are preferred. In particular, glass fibers areconveniently used. More than one kind of inorganic fibers may besuitably used in combination, or those of different average fiberlengths or fiber diameters may be used in combination. Where glassfibers are used, those of different glass compositions may be suitablyused in combination.

[0020] As such inorganic fibers, those having an average fiber length of50 μm-1.5 mm, preferably 50 μm-1.2 mm, and an average fiber diameter of2 μm-20 μm, preferably 5 μm-15 μm, are conveniently used. It issufficient that the average fiber length falls within the above range inthe completed shaped catalyst. Therefore, besides using inorganic fiberswhose average length is advancedly adjusted to 50 μm-1.5 mm, it ispermissible to mix inorganic fibers having an average length exceeding1.5 mm with a part or the whole of a catalytic composition and break thefibers under vigorous agitation to eventually render their averagelength to fall within the range of 50 μm-1.5 mm. The latter practice,however, tends to aggravate dispersibility of the inorganic fibers. Useof inorganic fibers whose average fiber length and average fiberdiameter deviate from the ranges of 50 μm-1.5 mm and 2 μm-201 μm,respectively, gives rise to problems such as that catalyst of uniformperformance cannot be obtained, and therefore is objectionable.

[0021] Suitable inorganic fiber content based on the weight of thecatalyst is 0.01-30%, preferably 0.05-20%, inter alia, 0.1-10%, thepercentages being by weight. Where the content is too low, the effect ofimproving the catalyst's mechanical strength is insufficient, and whereit is too high, the catalyst composition contained in the catalystbecomes less and the catalytic performance is degraded.

[0022] Those catalysts of the present invention can be preparedfollowing those methods generally used for preparing known catalysts forproduction of unsaturated aldehyde and unsaturated carboxylic acid,excepting the point of adding inorganic fibers to catalyst compositionand shaping the system into rings.

[0023] More specifically, a satisfactory catalyst can be prepared byadding inorganic fibers to, for example, a catalyst compositionexpressed by said general formula (1), and then shaping the system intorings by a conventionally used shaping method such as extrusion molding,pressing or the like. Manner of adding the inorganic fibers is notcritical, and any method may be used so long as it is capable ofsecuring uniformly dispersed presence of the added inorganic fibers inthe finished catalyst. For example, inorganic fibers may be added to thestarting compounds for a catalyst composition and the resulting slurryis dried and shaped, followed by calcinations; or a catalyst compositionis dried, calcined and pulverized, and inorganic fibers are added to theresulting powder, thoroughly mixed and the mixture is shaped. Inparticular, the former method is favorable because it gives a catalystexhibiting improved mechanical strength, yield of object products andcatalyst life, with good reproducibility. The calcinations treatment isnormally conducted at temperatures ranging 400-800° C. The inorganicfibers may be added all at once or in divided portions. For example, apart of them may be added to a slurry containing starting compounds andthe rest, to the dried and calcined powder.

[0024] In the occasion of shaping, conventionally used binder such aspolyvinyl alcohol, stearic acid, ammonium nitrate, graphite, water,alcohol and the like may be used if necessary.

[0025] The ring-formed catalyst grains preferably each has an outerdiameter of 3-10 mm, 0.1-0.7 time the outer diameter of an innerdiameter and 0.5-2 times the outer diameter of a length (height).

[0026] The catalytic vapor-phase oxidation reaction according to theinvention can be performed following generally practiced method forcatalytic vapor-phase oxidation of isobytylene, t-butanol or propyleneusing molecular oxygen, to produce corresponding methacrolein andmethacrylic acid, or acrolein and acrylic acid, excepting the point thatabove-described shaped catalyst is used as the catalyst. For example, agaseous mixture composed of 1-10 vol. % of isobutylene, t-butanol orpropylene, 3-20 vol. % of molecular oxygen, 0-60 vol. % of steam and20-80 vol. % of an inert gas such as nitrogen, carbon dioxide and thelike may be introduced over said shaped catalyst at a temperature withina range of 250-450° C., under normal pressure to 1Mpa and at a spacevelocity of 300-5,000h⁻¹ (STP).

[0027] In practicing the catalytic vapor-phase oxidation according tothe present invention, obviously such a method may be used as fillingeach reaction tube with two or more kinds of the catalysts differing inactivity levels, which are prepared by varying the composition,calcining condition, size or shape of the catalysts, as stacked inlayers so that the catalytic activity successively rises from the gasinlet toward the gas outlet of the reaction tube, to inhibit heataccumulation at hot spots, or any of various other known inhibitionmethods.

[0028] Effect of the Invention

[0029] According to the invention, catalysts which are high inmechanical strength, capable of giving unsaturated aldehyde andunsaturated carboxylic acid, which are the object products, at highyields, and have uniform catalytic performance showing little decreasein catalytic activity (yield reduction) with time can be prepared withease. According to the present invention, furthermore, acrolein andacrylic acid or methacrolein and methacrylic acid can be produced athigh yields over long periods.

EXAMPLES

[0030] Hereinafter the invention is explained more specifically,referring to working examples. The conversions and yields as given inthe Examples and Comparative Examples are defined as follows:${{comversion}\left( {{mol}\quad \%} \right)} = {\frac{\left( {{mol}\quad {number}\quad {of}\quad {reacted}\quad {starting}\quad {material}} \right)}{\left( {{mol}\quad {number}\quad {of}\quad {starting}\quad {material}} \right)} \times 100}$${{yield}\quad \left( {{mol}\quad \%} \right)} = {\frac{\begin{matrix}\left( {{total}\quad {mol}\quad {number}\quad {of}\quad {formed}\quad {unsaturated}\quad {aldehyde}} \right. \\\left. \quad {{and}\quad {formed}\quad {unsaturated}\quad {carboxylic}\quad {acid}} \right)\end{matrix}}{\left( {{mol}\quad {number}\quad {of}\quad {starting}\quad {material}} \right)} \times 100}$

[0031] The performance tests and shatter strength test of the catalystswere conducted by the following methods.

[0032] Catalytic Performance Test-1

[0033] One-hundred(100)ml of a catalyst was filled in a steel reactiontube of 25 mm in inner diameter, into which a gaseous mixture composedof 6 vol. % of isobutylene, 13 vol. % of oxygen, 15 vol. % of steam and66 vol. % of nitrogen was introduced. The reaction was conducted at aspace velocity of 1600 h⁻¹ and a reaction temperature of 340° C. Thereaction gas after 30 hours was analyzed.

[0034] Catalytic Performance Test-2

[0035] Fifteen-hundred(1,500)ml of a catalyst was filled in a steelreaction tube of 25 mm in inner diameter, and into which a gaseousmixture composed of 6 vol. % of isobutylene, 13 vol. % of oxygen, 15vol. % of steam and 66 vol. % of nitrogen was introduced. The reactionwas conducted at a space velocity of 1600 h⁻¹ and a reaction temperatureof 340° C. The reaction gas after 8,000 hours was analyzed.

[0036] Catalytic Performance Test-3

[0037] One-hundred(100)ml of a catalyst was filled in a steel reactiontube of 25 mm in inner diameter, and into which a gaseous mixturecomposed of 7 vol. % of propylene, 14 vol. % of oxygen, 25 vol. % ofsteam and 54 vol. % of nitrogen. The reaction was conducted at a spacevelocity of 1800h⁻¹ and a reaction temperature of 310° C. The reactiongas after 30 hours was analyzed.

[0038] Shatter Strength Test

[0039] Thirty(30)g of a catalyst was dropped from the top of aperpendicularly erected stainless steel pipe of 25 mm in inner diameterand 5 m in length, and received with a 4-mesh sieve. The weight of thecatalyst remained on the sieve was measured and the shatter strength ofthe catalyst was determined, applying the following equation:${{Shatter}\quad {{strength}(\%)}} = {\frac{\left( {{weight}\quad {of}\quad {catalyst}\quad {remained}\quad {on}\quad {the}\quad {sieve}} \right)}{\left( {{weight}\quad {of}\quad {dropped}\quad {catalyst}} \right)} \times 100}$

Example 1

[0040] Six-thousand(6,000)ml of water was heated to 40° C., and intowhich 2118 g of ammonium paramolybdate and 530 g of ammoniumparatungstate were dissolved under stirring. Thus a solution (liquid A)was prepared. Separately, 486 g of bismuth nitrate was dissolved inaqueous nitric acid solution composed of 60 ml of nitric acid(concentration: 65 wt %) and 240 ml of water to prepare another solution(liquid B). Again separately, 2912 g of cobalt nitrate and 404 g offerric nitrate were dissolved in 2000 ml of water to form a solution(liquid C), and 78.0 g of cesium nitrate was dissolved in 400 ml ofwater to form a solution (liquid D). Then into the liquid A underheating and stirring, the liquid B, liquid C and liquid D were addeddropwise by the order stated, and mixed. Further 406 g of 20 wt % silicasol and 68.9 g of alkali-free glass fibers of 10 μm in average fiberdiameter and 500 μm in average fiber length were added to the mixture,followed by thorough stirring.

[0041] Thus obtained suspension was heated under stirring to evaporatethe system to dryness, and the resulting solid matter was shaped intorings of 6.0 mm in outer diameter, 1.0 mm in inner diameter and 6.6 mmin length each, which were calcined at 500° C. for 6 hours while passingair, to provide a catalyst.

[0042] The composition of this catalyst excluding the glass fibers andoxygen was:

[0043] Mo₁₂W₂Bi₁Fe₁Co₁₀Cs_(0.4)Si_(1.35)

[0044] and its glass fiber content was 2.0 wt %.

[0045] The catalytic performance test-1 and shatter strength test wereconducted using this catalyst. The catalytic performance, pressure lossduring the reaction time and shatter strength of this catalyst are shownin Table 1.

Examples 2-9 and Comparative Examples 1-4

[0046] Example 1 was repeated except that the used glass fibers or shapeof the catalyst were changed as shown in Table 1, to prepare catalysts.

[0047] The catalytic performance test-1 and shatter strength test wereconducted using these catalysts. Their catalytic performance, pressureloss during the reaction time and shatter strength are shown in Table 1.TABLE 1 Added Catalyst shape Total yield of Pressure loss amount ofouter diameter × methacrolein + during inorganic inner diameter ×Isobutylene methafcrylic Shatter reaction Inorganic fibers lengthconversion acid strength time Fibers (wt %) (mm) (mol %) (mol %) (%)(kPa) Example 1 Glass fibers 2.0 6.0 × 1.0 × 6.6 99.1 89.1 98.5 16.4 (10μmØ/500 μm-long) Example 2 Glass fibers 2.0 6.0 × 1.0 × 6.6 98.9 89.098.1 16.2 (7 μmØ/500 μm-long) Example 3 Glass fibers 2.0 6.0 × 1.0 × 6.699.0 89.2 97.9 16.7 (13 μmØ/500 μm-long) Example 4 Glass fibers 2.0 6.0× 1.0 × 6.6 98.8 89.1 98.8 16.5 (10 μmØ/150 μm-long) Example 5 Glassfibers 2.0 6.0 × 1.0 × 6.6 98.9 88.8 94.9 17.2 (10 μmØ/3 mm-long)Example 6 Glass fibers 0.5 6.0 × 1.0 × 6.6 99.0 88.7 95.5 17.3 (10μmØ/500 μm-long) Example 7 Glass fibers 7.0 6.0 × 1.0 × 6.6 99.2 89.099.1 16.4 (10 μmØ/500 μm-long) Example 8 Glass fiber mixture 2.0 6.0 ×1.0 × 6.6 98.9 89.6 99.0 16.8 (10 μmØ/500 μm-long & 2.0 10 μmØ/3mm-long)) Example 9 Glass fibers 2.0 5.0 × 3.0 × 5.5 99.2 90.2 95.4 13.1(10 μmØ/500 μm-long) Comparative — — 6.0 × 1.0 × 6.6 99.0 88.2 90.4 18.1Example 1 Comparative glass powder 2.0 6.0 × 1.0 × 6.6 99.1 88.4 89.718.0 Example 2 (40 μmØ) Comparative silicon carbide 2.0 6.0 × 1.0 × 6.699.0 88.3 99.1 15.4 Example 3 (0.4 μmØ/40 μm-long) Comparative — — 5.0 ×3.0 × 5.5 98.9 89.0 75.0 18.2 Example 4

Example 10

[0048] The catalytic performance test-2 was conducted using the catalystof Example 1. The results were: isobutylene conversion, 90.2 mol % andtotal yield of methacrolein plus methacrylic acid, 82.3 mol %.

Comparative Example 5

[0049] The catalytic performance test-2 was conducted using the catalystof Comparative Example 1. The isobutylene conversion was 85.1 mol % andthe total yield of methacrolein plus methacrylic acid was 76.6 mol %.

Example 11

[0050] Into 6,000 ml of water heated to 40° C., 2000 g of ammoniumparamolybdate and 50 g of ammonium paratungstate were dissolved understirring to form a solution (liquid A). Separately, 778 g of bismuthnitrate was dissolved in an aqueous nitric acid solution formed of 100ml of nitric acid (concentration: 61 wt %) and 400 ml of water toprovide a solution (liquid B). Again separately 1100 g of cobaltnitrate, 824 g of nickel nitrate and 572 g of ferric nitrate weredissolved in 2000 ml of water to form a solution (liquid C), and 7.6 gof potassium nitrate was dissolved in 100 ml of water to provide asolution (liquid D). Then into the liquid A under heating and stirring,the liquids B, C and D were added by the order stated under continualstirring and mixing, and further 242 g of 20 wt % silica sol and 151 gof alkali-free glass fibers of 10 μm in average fiber diameter and 500μm in average fiber length were added, followed by thorough stirring.

[0051] Thus obtained suspension was heated and stirred to be evaporatedto dryness, and shaped into rings of 6.0 mm in outer diameter, 1.0 mm ininner diameter and 6.6 mm in length each, which were calcined at 480° C.for 8 hours while passing air, to provide a catalyst.

[0052] The composition of this catalyst excluding the glass fibers andoxygen was:

[0053] Mo₁₂W_(0.2)Bi_(1.7)Fe1.5Co₄Ni₃K_(0.08)Si₁

[0054] and its glass fiber content was 5 wt %.

[0055] The catalytic performance test-3 and shatter strength test wereconducted using this catalyst to give a propylene conversion of 98.3 mol%, total yield of acrolein plus acrylic acid of 91.8 mol %, a pressureloss during the reaction time of 18.9 kPa and a shatter strength of98.9%.

Comparative Example 6

[0056] Example 11 was repeated except that no glass fiber was used, toprovide a catalyst.

[0057] The catalytic performance test-3 and shatter strength test wereconducted using this catalyst. The propylene conversion was 98.5 mol %,total yield of acrolein plus acrylic acid was 90.9 mol %, pressure lossduring the reaction time was 21.6 kPa and the shatter strength was94.1%.

[0058] In the following Example 12 and Comparative Example 7, two kindsof catalysts exhibiting different activity levels were stacked andfilled in the reaction tube in such a manner that the catalyst of thelower activity was located at the inlet side of the reaction tube andthat of the higher activity, at the outlet side of the reaction tube,and the reaction was conducted.

Example 12

[0059] [Preparation of Catalyst 1 to be Stacked]

[0060] Catalyst 1 for stacking was prepared as in Example 1, except thatthe amount of cesium nitrate was changed to 136.4 g and the rings wereshaped to have an outer diameter of 5.0 mm, an inner diameter of 3.0 mmand a length of 5.5 mm each.

[0061] The composition of this catalyst excluding the glass fibers andoxygen was:

[0062] Mo₁₂W₂Bi₁Fe₁Co₁₀Cs_(0.7)Si_(1.35)

[0063] and its glass fiber content was 2.0 wt %.

[0064] The results of conducting the catalytic performance test-1 andshatter strength test using this catalyst are shown in Table 2.

[0065] [Preparation of Catalyst 2 to be Stacked]

[0066] The procedures for preparing above Catalyst 1 were repeatedexcept that the amount of cesium nitrate was changed to 19.5 g, toprepare Catalyst 2 to be stacked.

[0067] The composition of this catalyst excluding the glass fibers andoxygen was:

[0068] Mo₁₂W₂Bi₁Fe₁Co₁₀Cs_(0.1)Si_(1.35)

[0069] and the glass fiber content was 2.0 wt %.

[0070] The results of conducting the catalytic performance test-1 andshatter strength test are shown in Table 2.

[0071] [Reaction]

[0072] The reaction was conducted under the same conditions to those ofthe catalytic performance test-2, through the reaction tube filled with750 ml of the Catalyst 1 at the gas inlet side and 750 ml of theCatalyst 2 at the gas outlet side, forming a stack. The catalyticperformance after 30 hours of the reaction is shown in Table 2.

Comparative Example 7

[0073] [Preparation of Catalyst 3 to be Stacked]

[0074] Catalyst 3 was prepared in the same manner as the Catalyst 1 inExample 12, except that no glass fiber was added.

[0075] The results of conducting the catalytic performance test-1 andshatter strength test using this catalyst are shown in Table 2.

[0076] [Preparation of Catalyst 4 to be Stacked]

[0077] Catalyst 4 was prepared in the same manner as the Catalyst 2 inExample 12, except that no glass fiber was added.

[0078] The results of conducting the catalytic performance test-i andshatter strength test using this catalyst are shown in Table 2.

[0079] [Reaction]

[0080] Filling 750 ml of said Catalyst 3 at the gas inlet side of thereaction tube and 750 ml of said Catalyst 4 at the gas outlet sidethereof in a stack, the reaction was performed under the same conditionsto those of the catalytic performance test-2. The catalytic performanceafter 30 hours of the reaction is shown in Table 2. TABLE 2 CatalystInorganic Added amount of composition Fibers Inorganic fibers (wt %)Example 12 Catalyst 1 Mo₁₂ W₂ Bi₁ Fe₁ Co₁₀ Cs_(0.7) Si_(1.35) Glassfibers 2.0 (10 μmØ/500 μm-long) Catalyst 2 Mo₁₂ W₂ Bi₁ Fe₁ Co₁₀ Cs_(0.1)Si_(1.35) Glass fibers 2.0 (10 μmØ/500 μm-long) Reaction Catalyst 1: 750ml Catalyst 2: 750 ml Comparative Catalyst 3 Mo₁₂ W₂ Bi₁ Fe₁ Co₁₀Cs_(0.7) Si_(1.35) — — Example 7 Catalyst 4 Mo₁₂ W₂ Bi₁ Fe₁ Co₁₀Cs_(0.1) Si_(1.35) — — Reaction Catalyst 3: 750 ml Catalyst 4: 750 mlCatalyst shape Total yield of outer diameter × Isobutylenemethacrolein + Pressure loss inner diameter × conversion methacrylicacid Shatter during reaction length (mm) (mol %) (mol %) strength (%)time (kPa) Example 12 Catalyst 1 5.0 × 3.0 × 5.5 96.0 88.3 98.4 13.2Catalyst 2 5.0 × 3.0 × 5.5 99.5 88.1 98.0 13.0 Reaction 99.5 91.8 — 12.9Comparative Catalyst 3 5.0 × 3.0 × 5.5 97.1 86.9 76.4 17.9 Example 7Catalyst 4 5.0 × 3.0 × 5.5 99.8 86.4 74.3 18.4 Reaction 99.7 90.2 — 18.5

1. A catalyst for preparation of unsaturated aldehyde and unsaturatedcarboxylic acid, which is characterized in that it is in the form ofring-shaped bodies composed of a catalyst composition containing atleast molybdenum and bismuth as the active ingredients and inorganicfibers.
 2. A catalyst according to claim 1, in which the inorganicfibers are at least one selected from glass fibers, alumina fibers,silica fibers and carbon fibers, and have an average fiber length offrom 50 μm to 1.5 mm and an average fiber diameter of from 2 μm to 20μm.
 3. A catalyst according to claim 1 or 2, which contains from 0.01 to30% by weight, based on the weight of the catalyst, of inorganic fibers.4. A catalyst according to any of claims 1-3, in which the ring-shapedbody has an outer diameter of 3-10 mm, 0.1-0.7 time the outer diameterof an inner diameter and 0.5-2 times the outer diameter of a length. 5.A catalyst according to any of claims 1-4, in which the catalystcomposition is one expressed by a general formulaMo_(a)Bi_(b)Fe_(c)A_(d)B_(e)O_(x) (in which Mo is molybdenum; Bi isbismuth; Fe is iron; A is at least one element selected among nickel andcobalt; B is at least an element selected among alkali metal elements,alkaline earth metal elements, thallium, phosphorus, tellurium,antimony, tin, cerium, lead, niobium, manganese, arsenic, zinc, silicon,aluminium, titanium, zirconium and tungsten; O is oxygen; a, b, c, d, eand x stand for the respective atomic numbers of Mo, Bi, Fe, A, B and O,where a is 12, b is 0.1-10, c is 0.1-20, d is 2-20; e is 0-30 and x is anumerical value determined by the extents of oxidation of the otherelements).
 6. A process for catalytic vapor-phase oxidation ofisobutylene, tertiary butanol or propylene using molecular oxygen toproduce respectively corresponding methacrolein and methacrylic acid oracrolein and acrylic acid, the process being characterized by using acatalyst as described in any of claims 1-5.